Drug & supplement interaction

Kefir + Omalizumab

Omalizumab brand name: Xolair.

Moderate Interaction
Medically reviewed by · Updated September 2026
The bottom line Moderate

Kefir has a moderate interaction with Omalizumab. Theoretically, kefir might increase the risk of bacterial and yeast infections in patients taking immunosuppressants.

Read the full interaction report
SeverityModerate
LikelihoodPossible
EvidenceD
What do Severity, Likelihood & Evidence mean?
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Interaction report

Kefir and Omalizumab

Here is the interaction we found between these two, with the evidence behind it.

Moderate

IMMUNOSUPPRESSANTS

Why this applies to Omalizumab

Omalizumab falls under IMMUNOSUPPRESSANTS — the group Kefir interacts with.

Theoretically, kefir might increase the risk of bacterial and yeast infections in patients taking immunosuppressants.

Kefir contains actively growing bacteria and yeast.
Severity Moderate Likelihood Possible Evidence D

Interaction has been documented in animal or in lab research, or the interaction has been documented in humans but is limited to case reports or conflicting clinical research exists.

Dr. Brian Staiger, PharmD, BCPS
Dr. Brian Staiger explains PharmD, Clinical Pharmacist

Here's the honest picture with kefir and Xolair (omalizumab). Kefir is a fermented drink full of live bacteria and yeast. The worry on file is that if your immune system is dampened, those live microbes could, in theory, raise the risk of an infection. But this is really a general caution for strong immune-suppressing medicines, and it comes only from lab-type evidence, not real patient cases.

The good news: omalizumab doesn't broadly shut down your immune system the way some transplant or chemo drugs do. It mostly targets the IgE pathway behind allergic asthma and hives. So for most healthy people, a normal serving of kefir is unlikely to be a problem. If you have a weakened immune system for other reasons, check with your pharmacist or doctor first.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Murofushi M, Mizuguchi J, Aibara K, Matuhasi T. Immunopotentiative effect of polysaccharide from kefir grain, KGF-C, administered orally in mice. Immunopharmacology 1986;12:29-35. PubMed
  2. Shiomi M, Sasaki K, Murofushi M, Aibara K. Antitumor activity in mice of orally administered polysaccharide from Kefir grain. Jpn J Med Sci Biol 1982;35:75-80. PubMed
  3. Rimada PS, Abraham AG. Polysaccharide production by kefir grains during whey fermentation. J Dairy Res 2001;68:653-61. PubMed
  4. De Vrese M, Keller B, Barth CA. Enhancement of intestinal hydrolysis of lactose by microbial beta-galactosidase (EC 3.2.1.23) of kefir. Br J Nutr 1992;67:67-75.

What These Ratings Mean

Every interaction above is graded three ways — here’s the key to each label.

Severity how clinically significant the interaction is
Major

Clinically significant. Avoid the combination, or use only under close professional supervision.

Moderate

Usually worth avoiding or managing — may need monitoring, a dose change, or timing apart.

Minor

Generally not serious. Be aware of it and mention it to your pharmacist.

Likelihood how strong the evidence is that the interaction actually happens in people
  • LikelyWell-controlled human studies have demonstrated the likely existence of this interaction.
  • ProbableInteraction has not been documented in well-controlled studies, however, the interaction has been demonstrated in some small human studies or in controlled animal studies in conjunction with multiple case reports.
  • PossibleInteraction has been documented in animal or in lab research, or the interaction has been documented in humans but is limited to case reports or conflicting clinical research exists.
  • UnlikelyInteraction has been demonstrated in animal or in lab research but has been shown not to occur in humans.
Evidence the quality of the studies behind the rating (graded A–D)
  • AHigh-quality meta-analysis (quantitative systematic review).
  • BCase-control study.
  • CConsensus.
  • DAnecdotal evidence.

These ratings are for information only. Never start, stop, or otherwise change your therapy before speaking with your provider.

Keep it in perspective

Kefir Also Interacts With Other Medications

Kefir has 120 moderate, 1 minor known drug interactions in our database — the Omalizumab one above is one of them. If you take anything else, check it against the full list below.

Moderate 120 Minor 1 No known interaction 2,709 (incl. Omalizumab)
Taking anything else?

Check Another of Your Medications Against Kefir

Covers the 2,830 medications we’ve checked against Kefir. Pick one to open its full report.

Everything else you take

See Every Supplement That Interacts With Omalizumab

This page covers Kefir only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Omalizumab page lists 53 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Active Hexose Correlated Compound (ahcc) (moderate), Alfalfa (moderate), American Ginseng (moderate), Andrographis (moderate) and Ashwagandha (moderate).

By severity: 52 moderate · 1 minor.

From our pharmacist’s overview on the Omalizumab page

“None of the 53 supplements on file for omalizumab (Xolair) carries a major rating, so this is a list to read with steady attention rather than alarm. Xolair treats allergic asthma and chronic hives by calming part of the immune system, and every entry here pulls the other way: these are immune-stimulating products, echinacea and astrag…”

Reviewed by 2 · Jul 18, 2026

Open the Omalizumab interaction page

One more smart check

Taking Kefir as Part of a Dietary Supplement Product? Check It for Interactions

We hold 29 real supplement products containing Kefir, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Kefir. Your product may carry other ingredients that interact with Omalizumab too, on top of Kefir — and those would not show on this page. Find your product and we’ll check every ingredient on its label:

How much people look this up

Where Kefir and Omalizumab Sit Against Everything Else

Out of every supplement and medication people look up on HelloPharmacist, here is where these two land this week — and which way each has been moving.

Supplement Kefir
Steady interest

#1,037 of 1,452 supplements looked up here in the last 7 days

29 days ago today
Medication Omalizumab
Steady interest

#2,292 of 2,830 medications looked up here in the last 7 days

29 days ago today

Position among everything looked up on this site, not a measure of how commonly either one is used or how important it is. A supplement can climb this list because of a news story. It counts every request to the page, automated ones included, and nothing here identifies anyone.

Supplement

About Kefir

What is Kefir?

  • Digestive health
  • Source of probiotics
  • Lactose intolerance support
  • General immune support
  • Gut microbiome balance

Kefir is a fermented drink made by adding kefir grains to milk (or sugar water), creating a tangy beverage rich in probiotics. It is generally a safe, nutritious food that may support gut health, but strong evidence for treating specific medical conditions is still limited. If you have a weakened immune system or other health concerns, check with your pharmacist or doctor first.

Read the full Kefir monograph & all interactions
Medication

About Omalizumab Injection

What Is Omalizumab Injection Used For?

Brand name: Xolair

Xolair is used for several allergy-driven conditions. It treats moderate to severe persistent asthma in adults and children 6 and older whose symptoms aren't controlled by inhaled steroids alone and who test positive for a year-round airborne allergen. It is also used as an add-on maintenance treatment for chronic rhinosinusitis with nasal polyps (ongoing sinus inflammation with polyp growths) in adults 18 and older who haven't responded well to nasal corticosteroids.

Xolair is also approved to reduce allergic reactions — including anaphylaxis — from accidental food exposure in adults and children aged 1 and older with IgE-mediated food allergy. It must be used alongside strict food avoidance, and it is not a substitute for emergency treatment like epinephrine. Finally, Xolair treats chronic spontaneous urticaria (persistent hives with no identified trigger) in adults and adolescents 12 and older who still have symptoms despite antihistamine treatment.

See full Omalizumab Injection drug information
Keep checking

Other Drugs & Kefir

Browse every other medication we’ve checked against Kefir — both the ones with a known interaction and the ones without. Select any drug for the full detail.

0Major
120Moderate
1Minor
2,708No known interaction
120 Moderate 1 Minor 2,708 No interaction
Moderate

120 interactions

Showing 60 of 120 moderate interactions — see all 120 on the Kefir page.

Minor

1 interaction

No interaction 2,708 drugs checked — show the list

We also checked Kefir against these medications and found no known interaction in our sources. Open any page to confirm.

Showing the 60 most looked-up of 2,708 medications checked with no known interaction — see the full Kefir list.

See the full Kefir interactions page
See every supplement checked against Omalizumab, ranked by severity
Sources

Sources & How We Checked

Interaction details are evidence-graded and sourced from the Natural Medicines database. The medication overview comes from MedlinePlus.

Content is written and reviewed by licensed HelloPharmacist pharmacists. See our data sources and editorial standards for how this information is built and checked.

Parts of this content are provided by the Therapeutic Research Center, LLC.

DISCLAIMER: Currently this does not check for drug-drug interactions. This is not an all-inclusive comprehensive list of potential interactions and is for informational purposes only. Not all interactions are known or well-reported in the scientific literature, and new interactions are continually being reported. Input is needed from a qualified healthcare provider including a pharmacist before starting any therapy. Application of clinical judgment is necessary.

© 2021 Therapeutic Research Center, LLC

Keep exploring
Kefir monograph › Uses, safety, and every drug interaction in one place Omalizumab supplement interactions › Every supplement checked against Omalizumab, ranked by severity Omalizumab Injection drug information › The full plain-English guide to this medication Supplement interaction checker › Check any supplement or product against your medications Browse medications A–Z › Every drug we've checked against herbs & supplements Ask a pharmacist › Free, personal answer from our licensed team
Pharmacist Counseling Corner

Taking Kefir and Omalizumab Together: Common Questions

Can you take Kefir with Omalizumab?
There is a moderate interaction, so it may be acceptable with monitoring or timing changes — but check with your pharmacist first. Read the full details on this page and confirm with your pharmacist before combining them.
How serious is the Kefir and Omalizumab interaction?
We rate it Moderate. This combination may require monitoring, a dose adjustment, or separating the times you take each one. Consult your pharmacist before using them together.

Written and reviewed by the HelloPharmacist editorial staff. Our editorial policy

Still Have a Question About Omalizumab and Kefir?

Our pharmacists answer your medication & supplement questions — free.

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This information is for education only and is not a substitute for professional medical advice. Always check with your pharmacist or doctor before starting, stopping, or combining supplements and medications.